1. Field of the Invention
The present invention relates to an inorganic nonaqueous electrolytic solution cell. In particular, the present invention relates to an inorganic nonaqueous electrolytic solution cell which suffers less voltage drop in an initial discharge period after storage and has a short restoring time of a discharge voltage.
2. Description of the Related Art
In an inorganic nonaqueous electrolytic solution cell comprising an oxyhalide which is in a liquid state at room temperature (25.degree. C.) (e.g. thionyl chloride, sulfuryl chloride, phosphoryl chloride, etc.) as a positive electrode active material and a solvent of an electrolytic solution and an alkali metal (e.g. lithium, sodium, potassium, etc.) as a negative electrode active material, since the positive electrode active material directly contacts the positive electrode, that is, thionyl chloride directly contacts lithium in the case of a thionyl chloride-lithium cell which is one of the typical example of the inorganic nonaqueous electrolytic solution cell, a film of an alkali metal chloride such as lithium chloride is formed on the negative electrode.
While the lithium chloride film is a coarse film in an early stage of the formation, it grows to form a dense film to inactivate the negative electrode, when the cell is stored at a high temperature or it is stored for a long time. As a result, when the cell is used after the storage at a high temperature or long-term storage, the voltage drops in the initial discharge period and the discharge voltage does not reach a desired voltage level. Accordingly, when such a cell is used as an actuating power source, the equipment may not function properly.
In particular, the degree of voltage drop in a whisker shape which appears instantaneously in a period of several hundred microseconds to several milliseconds after the start of discharge is considerable so that the application range of the cell is greatly restricted.
This voltage drop in the initial discharge period appears not only in a first use of a virgin cell after storage but also appears each time when the already used cell is reused after storage.
In view of the above problem of the voltage drop in the initial discharge period, it is proposed to suppress the voltage drop in the initial discharge period by the addition of a halogenated organic silane compound (cf. Japanese Patent KOKAI Publication No. 220279/1986) or an oxygen-containing organic silane compound (cf. Japanese Patent KOKAI Publication No. 3961/1989) to an electrolytic solution.
However, the addition of the halogenated organic silane compound or the oxygen-containing organic silane compound to the electrolytic solution cannot sufficiently suppress the large voltage drop in a whisker shape which appears instantaneously in a period of several hundred microseconds to several milliseconds after the start of discharge or acceleration of the restoration of the discharge voltage after the voltage drop.